Bubble type electrolytic reversible switch



Feb. 6, 1962 R. c. REMINGTON ETAL BUBBLE TYPE ELECTROLYTIC REVERSIBLE SWITCH Filed Dec. 9, 1959 3 Sheets-Sheet 1 1 TTaP/VE Y Feb. 6, 1962 R. c. REMINGTON ETAL 3,

BUBBLE TYPE ELECTROLYTIC REVERSIBLE SWITCH Filed Dec. 9, 1959 3 Sheets-Sheet 2 39 l A k i QQV/O JSCY/flZ/FFL E/Q Q0/4190 C. REMINGTON 1 INVENTORS 1962 R. c. REMINGTON ETAL 3,020,506

BUBBLE TYPE ELECTROLYTIC REVERSIBLE SWITCH Filed Dec. 9, 1959 3 Sheets-Sheet 3 Q R/CHA RD C. ,QEM/NGTOA/S' INVENTOR.

' 041/09 JSCl/AUFFL 5Q United States Patent 3,020,506 BUBBLE TYPE ELECTROLYTIC REVERSIBLE SWITCH Richard C. Remington, PomptonPlains, and David J.

Schautiler, Orange, N.J., assignors to General Precision, Inc., a corporation of Delaware Filed Dec. 9, 1959, Ser. No. 858,471 8 Claims. (Cl. 33886) The invention relates to electrolytic switches or sensing elements, and is particularly directed to a bubble type of switch or sensing element, which will indicate the angular position of the axis of the switch relative to the nomina-l vertical position thereof, the device being employed to measure the angular offset of the switch from the nominal vertical position thereof, and convert the angular offset to an electrical signal which may be transmitted to other devices.

The primary feature of the device, is that the eifectiveness, and measuring characteristics thereof, are independent of the attitude of the device, relative to the normal position thereof, so that it is equally effective whether it be mounted in one position, with the contacts fitted to the top of the case, or reversed with the contacts projecting through the bottom of the case, or at any intermediate angle between these two extremes.

While devices of this general character have been available for some time, they are usually limited to devices which are suitable for operation in one attitude only, that is in a position in which the contacts which engage the surface of the eelctrolytic liquid and the bubble formed therein are located above the electrolyte, as the bubble formed in devices of this type is generally located at the top of the electrolytic fluid so that if a device of this type is reversed, that is with the'contacts located below the electrolytic fluid, they are ineifectual as the bubble is formed at the top, out of engagement with the surfaces of the contacts. I

With applicants apparatus, the height of the space available for the electrolyte is reduced to a point at which the'bubble extends through the entire height of the liquid electrolyte. With this construction, the device can be utilized for measuring the angular displacement from the vertical, with equal facility, whether the faces of the contacts are located above or below the area in which the electrolytic fluid is contained, as the bubble in extending through the entire height of the electrolyte is equally effective in determining the angular displacement from the vertical, whether the contacts are above or below the fluid, or at any intermediate angle therebetween.

- With modern high speed aircraft and missiles, the craft is frequently flown in such an attitude that the gyro of the navigation system is either reversed from its normal position, or angularly displaced relative thereto, so that the device, such as the angular sensing element, or switch, which is used for measuring the angular displacement from the vertical, may be used in either its nominal position, reversed therefrom, or within any intermediate angular attitude.

Another feature of the device is that it can be pro duced in two types, in one of which, which is normally used for two-axis measurement, two pair of contacts, one pair of which is located on an axis substantially perpendicular to the axis through the other pair, are provided. In the second type only two contacts are used, the contacts being located on a single axis, so that angular displacement in only one axis relative to the vertical, can be measured by the device and transmitted as electrical signals to an external apparatus.

Another feature of the device is that it may be produced in two separate and distinct types. In one type a 3,020,506 Patented Feb. 6, 1962 cupped metal container is provided, a glass plate being sealed into the open end of the container, so that the electrolyte is contained in a completely sealed comp-artment to prevent leakage.

In a modification of the construction, the entire unit is formed of glass, with a thin metal wafer inserted in the area in which the electrolyte is stored, suitable contacts being molded into and fixedly attached to the opposite wall of the container in contact with the electrolytic fluid, thus again providing a positvely sealed compartment, in which the electrolyte is stored.

Another feature of the construction is that the distance between one wall of the electrolyte storage compartment, and the'opposite wall thereof is held relatively small and accurately determined and controlled, to assure a continuous bubble, which extends from the upper to the lower end of the electrolyte compartment.

The accompanying drawings, illustrative of one embodiment of the invention, and several modifications thereof, together with the description of their construction and the method of operation, adjustment, control and utilization thereof, will serve to clarify further objects and advantages of our invention.

In the drawings:

FIGURE 1 represents a vertical section through one embodiment of the device, including a hollow metal container and a glass plate fitted to the top thereof.

FIGURE 2 is a plan view of the sensing element shown in FIGURE 1, showing the relation between the contacts. 7

FIGURE 3 is a vertical section similar to FIGURE 1, through a modification of the construction shown in FIGURE 1, in which an all glass container is substituted in place of the metal and glass combination, shown in FIGURES l and 2.

FIGURE 4 is a vertical section, similar to FIGURE 1, through a modification of the apparatus shown in FIGURES 1 and 3, in which only two contacts are utilized to provide a single axis type of unit.

FIGURE 5 is a plan view of the modified device shown in FIGURE 4, showing the relationbetween the two contacts.

FIGURE 6 is a schematic Wiring circuit, showing the method of connecting the sensing element to a torque motor to transmit the angular position of the sensing element to a remotely mounted angle control device.

It will be understood that the following description of the construction and the method of mounting, attachment, operation, circuitry and utilization of the electrolytic vertical sensing element, is intended as explanatory of the invention and not restrictive thereof.

In the drawings, the same reference numerals designate the same parts throughout the various views, except where otherwise indicated.

One embodiment of the construction, shown in FIG- URES 1 and 2, comprises a hollow case 10 of substantially circular cross-section, the case having an enlarged circular open section 11, at the upper section thereof, into which a thick glass plate 14, is molded to provide a positive seal between the case 10, and the glass plate.

The glass plate has a total of four precious metal or other type of metal contacts 15, 16, molded into it, the contacts being located in two pairs 15, 15a, and 16, 16a, the axis of one pair of contacts in the plane of the glass plate, being substantially perpendicular to that of the other pair.

Each of the contacts 15, 16 includes a flat disc 17 of circular, or substantially rectangular contour, the outer surface of the disc projecting through the glass plate, and a substantially cylindrical stem 18, integral with the disc, the stem being inserted through and molded into the glass plate 14, the flat disc extending intoa sealed electrolyte compartment 19, the upper surface of the electrolyte compartment being flat, with the bottom surface of the compartment of relatively shallow, substantially conical contour.

A shallow cup 21, formed of relatively thin platinum is fitted to the lower portion of the case, the flat conical bottom wall 22 of the cup forming the bottom surface of the electrolyte compartment 19. The open upper end of the platinum cup, has a substantially circular flange 23, integral therewith, the flange resting against an inwardly projecting ledge which extends inward from the open upper portion of the case 10, the flange being molded into the bottom surface of the glass plate 14, to form a positive seal between the inner surface of the glass plate 14 and the interior of the platinum cup.

The inner circular area of the platinum cup, and a portion of the relatively conical bottom surface thereof, is coated with glass 24, the glass coating being applied by depositing powdered glass around the surfaces of the platinum cup to be coated, and firing the glass to form a positive bond between the glass coating and the interior of the platinum cup 21, the glass coating forming a portion of the interior of the electrolyte compartment.

The gap between the bottom surface of the glass plate, and the inner surface of the flat conical botttom of the platinum cup is held to a relatively short distance and accurately maintained so that the height of the central bubble 26, formed at substantially the center of the electrolytic fluid 27 which is stored in the electrolyte compartment 19 extends over the entire height of the electrolyte compartment 19.

A coiled spring 28, formed of wire of circular crosssection, is inserted into the interior of the case 10, between the outer surface of the platinum cup 21 and the inner surface of the case to engage the outer surface of the platinum cup 21 and press it upward against the electrolytic fluid, the spring being adapted to ground the platinum insert cup 21 and the electrolytic fluid contained therein, through the case 10, the spring having a formed lip 30 integral with the circumferential outer end thereof, the lip extending through a small circular opening through the flat outer wall 31, of the case, and being soldered or otherwise attached thereto, to positively support the spring 28, relative to the case.

The center of the bottom wall of the case has a small vent opening 32 therethrough A small filler tube 33 of circular cross-section is molded into the glass plate, at substantially the center thereof, to allow the electrolytic fluid to be inserted therethrough into the electrolyte compartment 19, the outer end of the tube being sealed 34, after the requisite quantity of electrolytic fluid is inserted therethrough, to positively "seal the electrolyte compartment.

The volume of electrolytic fluid poured into the compartment, which is a substantially fixed percentage of the volume of the electrolyte compartment may be determined by actually measuring the clear volume of the electrolyte compartment and pouring a quantity of fluid representing a fixed percentage thereof into it to obtain a "specific bubble diameter, or by pouring a preliminary volume of electrolytic fluid into the compartment, and electrically measuring the current transmitted from the one of the contacts through the electrolytic fluid to the platinum cup to the opposite contact. As this is a direct function of the area of electrolytic fluid in contact with the exposed disc of each of the contacts 15, 16, it is an accurate measure of the size of the bubble formed in the center of the electrolytic fluid.

While not generally fixed at this point, the diameter of the bubble, at the surface of engagement with the contact discs, is generally made substantially equal to the spacing between the axes of opposite contacts 15, a.

The outer circumference of the case 10 at the junction with the enlarged section 11 thereof, has a flat substantially circular flange 35 integral therewith, the flange having a pluarality of elongated slots 36 therethrough to enable the case to be attached to a mounting surface.

The switch or sensing element is mounted on a gyro platform, or other device to indicate the angular offset of the gyro gimbal or other mounting point of the switch, relative to the nominal vertical axis 37 of the switch, the opposite contacts of the switch being connected to a torquer motor 38, which is connected to opposite contacts 15, 15a of the switch, as shown in the wiring circuit, FIG- URE 6, the torquer motor being adapted to receive the electrical signal, indicating the degree of variation of the switch axis, from the nominal vertical axis 37 thereof, and restore the gyro gimbal (not shown) to its normal position in alignment with the normal vertical axis 37 of the switch or sensing element.

While not necessarily controlling, the electrolytic fluid, consists of normal butyl alcohol, with an iodide conductor, the iodide conductor serving to conduct the current from one contact 15 through the electrolytic fluid, and out through the opposite contact 15a.

The lip 30 of the circular spring 28 serves to ground the platinum cup, through the case 10, the current passing through the flange 35 of the case to an external ground connection, through the central ground connection 39 of the electrolytic switch, shown in FIGURE 3.

After filling and sealing the electrolyte compartment 19, the operation of the sensing element is substantially as follows:

When the axis of the device is angularly offset, relative to the nominally vertical position, thereof, shown in FIG- URE 1, the fluid level is tilted by tilting the entire case, the bubble 26 being displaced so that the fluid partially uncovers a portion of the disc of one of the contacts 15 and covers a larger area of the disc of the diametrically opposite contact 150.

This increases or decreases the flow of current through the contacts 15, 15a, depending upon the direction of the angular displacement of the axis of the case, the differential current being transmitted to a torquer motor 38, as shown on the wiring circuit, FIGURE 6, the torquer motor being adapted to restore the gyro gimbal to its nominally vertical position in a manner hereinafter described.

When the case 10 is reversed, and the flat faces of the contacts 15, 16 are below the surface of the electrolytic fluid, in a position such as that shown in FIGURE 3, the operation is substantially the same, as the bubble 26 runs entirely through the electrolytic fluid, the current differential between the contacts 15, 15a being substantially the same, whether the contacts are located above or below the electrolytic fluid.

When the case is tilted in a plane, through the axis of the other pair of the contacts 16, 160, the flow of current through the contacts 16, 16a is varied in the same manner as that through the contact 15, 15a, thus transmitting the current variations to another torquer motor mounted in this plane, and restoring the gyro gimbal to its nominally vertical position in this plane.

In a modification of the construction, shown in FIG. URE 3, the container 41 is made entirely of glass, the cap 42, thereof, into which the contacts 43, 44 are molded being welded or otherwise fixedly attached to the circular wall of the cupped cylindrical body section 45 of the case.

A relatively shallow dished platinum disc 46 of frustoconical, or other suitable form, is inserted into the interior of the electrolytic compartment of the container 41, adjacent the inner surface of the outer wall 47 of the case, which is also of shallow frusto-conical form, following substantially the contour of the disc 46, a ground connection 39, inserted through a boss 49 integral with the dished outer wall 47 of the case, and attached to the dished platinum disc, serving as a ground connection, the dished outer wall of the container 41 being bonded to the ground connection.

The electrolytic fluid 27 may be inserted through an opening through the cap wall 42 of the case, which is later sealed, or through the ground connection 39, which may be tubular and sealed at the open end thereof, after the electrolytic fluid is inserted therethrough.

The height of the electrolyte compartment 51 from the inner surface ofthe cap 42 of the container to the inner surface of the dished platinum disc 46 inserted into the interior of the container adjacent the dished outer wall 47 thereof, is substantially the same as that of the case shown in FIGURE 1, so that the bubble 26 formed at the center of the electrolytic fluid extends through from the inner surface of the dished disc 46 to the inner surface of the cap of the container in the same manner as that shown in FIGURE 1.

The discs 52, 53 integral with the contacts 43, 44, which are aligned with the inner surface of the glass cap 42 of the container, engage the adjacent surface of the electrolytic fluid 27 in substantially the same manner as that shown in FIGURE 1.

The container 41 is fitted to a hollow substantially circular outer case 55 made of metal, which surrounds and supports the container, a flange 56 integral with the circumferential outer surface of the outer case being provided to mount the sensing element, in substantially the same manner as that shown in FIGURE 1.

The operation of the switch or sensing element shown in FIGURE 3, is substantially the same as that shown in FIGURE 1, the contacts 43 and 44 indicating the angular offset of the vertical axis of the unit in substantially the same manner as that shown in FIGURE 1.

This applies, whether the switch is mounted with the contacts 43, 44 above the electrolytic fluid 27 as shown in FIGURE 1, or below the electrolytic fluid in the manner shown in FIGURE 3, as the bubble 26 extends through the entire height of the electrolyte compartment 51, so that the current differential reading between the contacts 43, 44 is substantially the same whether the sensing element is mounted in one position or the other.

FIGURE '6 represents a schematic wiring diagram of the sensing element connected to a torquer motor 38 which is mounted on the gimbal of a gyro or a gyro platform, which forms part of a navigation system of an airplane or other vehicle.

The current flows from a source 59 through the torquer motor 38, the terminals '60, 61 which are connected to two of the contacts 15, a of the vertical sensing element, the ground connection, which is attached to the interior of the dished platinum disc 46, or the ground connection which is connected to the spring 28, of the unit shown in FIGURE 1, being connected to a ground line 62.

The operation of the sensing alignment is as hereinbefore described. When the container shown in FIG- URE l is tilted to the left, the area of electrolytic fluid in contact with the disc 17 of the left-hand contact 15 is increased, whereas the area in contact with the disc of the right-hand contact 15a is decreased, so that the flow of current through the left-hand contact, and therefore the current differential through the left-hand terminal 60 of the torquer motor 38 is increased. This causes the torquer motor to rotate clockwise, left-hand arrow 64, FIGURE 6, the torquer motor 38 restoring the axis of the sensingelement to its initial substantially vertical position.

When the container shown in FIGURE 1 is tilted rightward, the reverse is true, the current through the right-hand terminal 61 of the torquer motor being increased, thereby causing the torquer motor to rotate counter-clockwise, right-hand arrow 65, the torquer motor restoring the axis of the container to its initial substantially vertical position.

In another modification of the construction shown in FIGURES 4 and 5, which is a single-axis sensing element,

the container 68 is made of glass in the same manner 6 as that shown in FIGURE 3, the only difference being that it is of oval cross-sectional contour, as shown in FIGURE 5, instead of circular.

The cap 67 of the container, which is made of glass has two contacts 69, 70 supported thereby and fitted thereto, the contacts being located on a single axis 71 through the center of the container. The two discs 73, 72 integral with the end of the contacts are aligned with the inner surface of the cap of the container, in the same manner as those shown in FIGURE 3.

The electrolytic fluid 74 in the interior of the container is substantially the same as that shown in FIG- URE 3, except that less fluidis used, due to the smaller oval cross-sectional contour of the container.

The dished platinum disc 75 inserted in the interior of the container adjacent the correspondingly dished base thereof is substantially the same as that shown in FIGURE 3, the dished disc having a ground connection 76, attached thereto, and extending through the dished glass base 77 of the container body in the same manner. The bubble at the center of the electrolytic fluid is substantially the same as that shown in FIGURE 3, the bubble 26 extending entirely through the electrolytic fluid, from the inner surface of the cap 67 of the container, to the inner surface of the dished platinum disc.

The operation of this type of unit is substantially the same as that shown in FIGURES l and 3 and hereinbefore described, except that it indicates the angular offset in one plane only, the plane through the axis of the two contacts 69, 70. T

This applies whether the contacts are located above the electrolytic fluid in the position shown in FIGURE 1 or below it, with the container reversed, in the position shown in FIGURES 3 and 4, as the bubble extends entirely through the electrolyte compartment, so that the electrolyte and the bubble make contact with the contact discs 72, 73 of the contacts 69, 70 regardless of the position of the contacts, relative to the electrolytic fluid. Instead of an all-glass container, such as that shown in FIGURE 4, a metal case fitted with a glass plate 14, such as that shown in FIGURE 1, may be substituted, the location of the contacts 69, 70 and the operation of the apparatus remaining substantially the same.

A cupped metal outer case 78, would surround the lower portion of the container in the same manner as that shown in FIGURE 3, the outer case having a flat mounting flange 79 in substantially the same location.

It will be apparent to those skilled in the art, that the present invention is not limited to the specific details described above and shown in the drawings, and that various modifications are possible in carrying out the features of the invention and the operation and the method of connection, mounting and utilization thereof, without departing from the spirit and scope of the appended claims.

What is claimed is:

, 1. An electrolytic sensing element comprising a cup shaped case, a seal cap of an electrically insulating ma terial fixedly attached to the open end of the case to seal the case, a cup shaped metallic insert fitted to the interior of the case to form an electrolyte compartment therein, the height of said electrolyte compartment between the inner face of the seal cap and the inner surface of the metallic insert being relatively small, a plurality of pairs of diametrically aligned contacts supported by the seal cap, eachof said contacts having an exposed surface thereof directed toward the electrolyte compartment, a

predetermined quantity of electrolytic fluid inserted into said electrolyte compartment, the electrolytic fluid quantity being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the case being made of relatively thin metal, the seal cap being a transparent plate sealed into the open end of the case, a coiled spring inserted into the case, between the inner surface of the case and the bottom of the metallic insert, said coiled spring having a lip integral therewith and projecting therefrom, the wall of the case, adjacent the spring, having an opening therethrough, the lip of the spring extending through the opening through the wall of the case to provide a ground connection to the metallic insert.

2. An electrolytic sensing element comprising a cup shaped case, a seal cap of an electrically insulating material fixedly attached to the open end of the case to seal the case, a cup-shaped metallic insert fitted to the interior of the case to form an electrolyte compartment therein, the height of said electrolyte compartment between the inner face of the seal cap and the inner surface of the metallic insert being relatively small, a plurality of pairs of diametrically aligned contacts supported by the seal cap, each of said contacts having an exposed surface thereof directed toward the electrolyte compartment, and a predetermined quantity of electrolytic fluid inserted into said electrolyte compartment, the electrolytic fluid quantity being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the case being made of thin metal, the seal cap being a transparent plate sealed into the open end of the case, the case having a mounting flange integral therewith and substantially perpendicular to the normal axis thereof, and spring means fitted to the case between the inner surface of the case and one face of the metallic insert, a portion of said spring means projecting through one wall of the case to provide a ground connection to the metallic insert.

3. An electrolytic sensing element comprising a cup shaped case, a seal cap of an electrically insulating material fixedly attached to the open and of the case to seal the case, a cup-shaped metallic insert fitted to the interior of the case to form an electrolyte compartment therein, the height of said electrolyte compartment between the inner face of the seal cap and the inner surface of the metallic insert being relatively small, a plurality of pairs of diametrically aligned contacts supported by the seal cap, each of said contacts having an exposed surface thereof directed toward the electrolyte compartment, and a predetermined quantity of electrolytic fluid inserted into said electrolyte compartment, the electrolytic fluid quantity being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the case being made of a relatively thin metal, the seal cap being a transparent plate sealed into the open end of the case,

each of the contacts including a disc section fitted to the inner surface of the seal plate, a portion of each of said contacts integral with the disc section projecting through the outer surface of the seal cap, the projecting portions of each diametrically aligned pair of contacts being adapted for electrical connection to an external point, to transmit electrical signals from the electrolytic fluid area in engagement with the disc sections of each pair of diametrically aligned contacts, to indicate the angular displacement of the case relative to the normal axis there of, and compressible means fitted to the case, in engagement with one face of the metallic insert, means integral with said compressible means projecting through one Wall of the case, to provide a ground connection to the metallic insert.

4. An electrolytic sensing element comprising a cup shaped case, a seal cap of an electrically insulating material fixedly attached to the open end of the case to seal the case, a cup-shaped metallic insert fitted to the interior of the case to form an electrolyte compartment therein, the height of said electrolyte compartment between the inner face of the seal cap and the inner surface of the metallic insert being relatively small, a plurality of pairs of diametrically aligned contacts supported by the seal cap, each of said contacts having an exposed surface 8 thereof directed toward the electrolyte compartment, a predetermined quantity of electrolytic fluid inserted into said electrolyte compartment, the electrolytic fluid quantity being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the case being made of metal, each of the contacts including a disc section fitted to the inner surface of the seal cap, a portion of each of said contacts, integral with the disc section, projecting through the outer surface of the seal cap, the projecting sections of each pair of contacts being adapted for electrical connection to an external point, to transmit electrical signals from the area of electrolytic fluid in engagement with the disc sections of a diametrically aligned pair of contacts, to indicate the angular displacement of the axis of the case relative to the normal axis thereof, regardless of the position of the contact disc sections relative to the surface of the electrolytic fluid, and spring means fitted to the case, between one wall of the case and one face of the metallic insert, a portion of said spring means extending through one wall of the case to provide a ground connection to the metallic insert.

5. An electrolytic sensing element for indicating angular displacement from a nominal axis, comprising a cup shaped case, a seal member of an electrically insulating material fixedly attached to the case, said seal member having a pair of diametrically aligned contacts fixedly attached thereto, a cup-shaped metal insert fitted to the interior of the case, the cup-shaped metal insert being adapted to form an electrolyte compartment in the case, between the seal member and the bottom of the cup-shaped metal insert, the height of said electrolyte compartment between the seal member and the metal insert being relatively small, relative to the length of the case, each of said contacts having a portion thereof projecting through the inner surface of the seal member, into the electrolyte compartment, a quantity of electrolytic fluid inserted into said electrolyte compartment, the quantity of electrolytic fluid being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, each of the contacts including a disc section fitted to the inner surface of the seal cap, a portion of each of said contacts, integral with the disc section, projecting through the outer surface of the seal cap, the projecting sections of the pair of contacts being adapted for electrical connection to an external point, to transmit electrical signals from the area of the electrolytic fluid in engagement with the projecting portion of the diametrically aligned pair of contacts, extending into the electrolyte compartment, to indicate the angular displacement of the axis of the case relative to the normal axis thereof, regardless of the position of the portion of the contacts, within the electrolyte compartment, relative to the surface of the electrolytic fluid, and spring means fitted to the case between one wall of the case and one face of the cup-shaped metallic insert, a portion of said spring means extending through one wall of the case to provide a ground connection to the cup-shaped metallic insert.

6. An electrolytic switch for indicating angular displacement from a nominal axis, comprising, a cup-shaped case, a seal member of an electrically insulating material fixedly attached to the open end of the case, said seal member having a plurality of pairs of diametrically aligned contacts fixedly attached thereto, a cup-shaped metallic insert fitted to the interior of the case to form an electrolyte compartment therein, the height of said electrolyte compartment, between the inner face of the seal cap and the inner surface of the cup-shaped metallic insert being relatively small, each of said contacts having an exposed surface thereof directed toward the electrolyte compartment, a quantity of electrolytic fluid inserted into said electrolyte compartment, the quantity of electrolytic fluid being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the case being made of metal, each of the contacts including a disc section fitted to the inner surface of the seal member, a portion of each of said contacts integral with the disc section projecting through the outer surface of the seal member, said projecting portion of the contacts being adapted for electrical connection to an external point to transmit electrical signals from the area of electrolytic fluid in engagement with the portion of the pair of contacts projecting toward the electrolytic compartment, to indicate the angular displacement of the axis of the case relative to the normal axis thereof, regardless of the position of the portions of the contacts relative to the surface of the electrolytic fluid, filler means inserted through said seal member in direct communication with the electrolyte compartment, means adapted to seal the filler means to seal the electrolyte compartment, and spring means fitted to the case, between one wall of the case and one face of the cup-shaped metallic insert, a portion of said spring means extending through one wall of the case to provide a ground connection to the metallic insert.

7. An electrolytic sensing element comprising a cupshaped container, a seal cap of an electrically insulating material fixedly attached to the open end of the container, to seal the container, a cup-shaped metallic insert fitted to the interior of the container to form an electrolyte compartment therein, the height of said electrolyte compartment between the inner face of the seal cap and the inner surface of the cup-shaped metallic insert being relatively small, a plurality of pairs of diametrically aligned contacts supported by the seal cap, each of said contacts having an exposed surface thereof directed toward the electrolyte compartment, and a predetermined quantity of electrolytic fluid inserted into said electrolyte compartment, the electrolytic fluid quantity being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the seal cap being a plate made of a transparent material fixedly attached to the open end of the container, each of the contacts including a disc section fitted to the inner surface of the seal cap, a portion of each of said contacts, integral with the disc section, projecting through the outer surface of the seal cap, the projecting portion of each of a diametrically aligned pair of contacts being adapted for electrical connection to an external point, to transmit electrical signals from the electrolytic fluid area in engagement with the disc sections of a diametrically aligned pair of contacts to indicate the angular displacement of the axis of the case relative to the normal axis thereof, regardless of the position of the contact disc sections relative to the surface of the electrolytic fluid, compressible means fitted to the container, in engagement with one face of the metallic insert, means integral with said compressible means projecting through one wall of the container, to provide a ground connection to the metallic insert, filler means inserted through said seal cap, in direct communication with the electrolyte compartment, and means adapted to seal the filler means to seal the electrolyte compartment. 7

8. An electrolytic sensing element for indicating angular displacement from a nominal axis, comprising a cupshaped case, a seal member of an electrically insulating material fixedly attached to the case, said seal member having a pair of diametrically aligned contacts fixedly attached thereto, a cup-shaped metallic insert fitted to the interior of the case to form an electrolyte compartment therein, the height of said electrolyte compartment between the inner face of the seal cap and the inner surface of the metallic insert being relatively small relative to the length of the case, each of said contacts having a portion thereof projecting through the inner surface of the seal member, into the electrolyte compartment, a quantity of electrolytic fluid inserted in said electrolyte compartment, the quantity of electrolytic fluid being limited relative to the volume of the electrolyte compartment to form a bubble through the electrolytic fluid, said bubble normally extending through the entire height of the electrolyte compartment, the case being made of relatively thin metal, the seal member being a relatively flat plate made of a transparent material fixedly attached to the open end of the case, each of the contacts including a disc section fitted to the inner surface of the seal member, a portion of each of said contacts integral with the disc section projecting through the outer surface of the seal member, the projecting portion of each of a pair of contacts being adapted for electrical connection to an external point to transmit electrical signals from the area of electrolytic fluid in engagement with the projecting portion of the diametrically aligned pair of contacts extending into the electrolyte compartment to indicatethe angular displacement of the axis of the case relative to the normal axis thereof, a coiled spring inserted into the case, between the inner surface of the case and the bottom of the metallic insert, said coiled spring having a lip integral therewith and projecting therefrom, the wall of the case, adjacent the spring, having an opening therethrough, the lip of the spring extending through the opening through the wall of the case to provide a ground connection to the metallic insert, filler means inserted through said seal member, in direct communication with the electrolyte compartment, and means adapted to seal the filler means to seal the electrolyte compartment.

References Cited in the file of this patent UNITED STATES PATENTS 2,367,465 Kunzer Jan. 16, 1945 2,376,377 Muma et a1 May 22, 1945 2,713,726 Dixson July 26, 1955 

